Merge pull request #4 from pinojs/wrapper

Alternative implementation of the meta wrapper

Readme.md

@@ -71,28 +71,34 @@ in [CLI Arguments](#cliargs):
   levelFirst: false, // --levelFirst
   localTime: false, // --localTime
   messageKey: 'msg', // --messageKey
-  translateTime: false, // --translateTime
-  useMetadata: false,
-  outputStream: process.stdout
+  translateTime: false // --translateTime
 }
 ```
 
-Unless `useMetadata` is set to `true`, the factory function returns the
-function: `function pretty (line) {}`. See the [next subsection](#usemetadata)
-for information on the other case.
+See the [next subsection](#usemetadata) for information on how to use this
+directly with `pino`.
 
 <a id="usemetadata"></a>
-### `useMetadata` and `outputStream`
+### pretty.asMetaWrapper(writable)
 
-If the `useMetadata` option is set to `true`, then the factory function will
-return an object that can be supplied directly to Pino as a stream that is
-compatible with Pino's [metadata stream API][mdstream]. This allows `pino-pretty`
-to skip the expensive task of parsing JSON log lines and instead work directly
-with Pino's log object.
+```js
+const factory = require('pino-pretty')
+const pino = require('pino')
+
+// writable is any Writable stream
+const writable = process.stdout
+const dest = factory({ colorize: true }).asMetaWrapper(writable)
+
+const logger = pino({}, dest)
+```
+
+The function returned by the factory has a `.asMetaWrapper(dest)` function attached
+which will return an object that can be supplied directly to Pino as a stream
+that is compatible with Pino's [metadata stream API][mdstream].
+This allows `pino-pretty` to skip the expensive task of parsing JSON log lines
+and instead work directly with Pino's log object.
 
-When `useMetadata` is set to `true` then the `outputStream` option dictates
-where the final formatted log line will be written. This must be a writable
-stream. The default stream is `process.stdout`.
+The default stream is `process.stdout`.
 
 [mdstream]: https://github.com/pinojs/pino/blob/fc4c83b/docs/API.md#metadata
 

index.js

@@ -76,20 +76,9 @@ module.exports = function prettyFactory (options) {
     color.message = ctx.cyan
   }
 
-  if (!opts.useMetadata) {
-    return pretty
-  }
+  pretty.asMetaWrapper = asMetaWrapper
 
-  const outputSym = Symbol('pino-pretty.out')
-
-  return {
-    [Symbol.for('needsMetadata')]: true,
-    [outputSym]: opts.outputStream,
-    write (chunk) {
-      const formatted = pretty(chunk)
-      this[outputSym].write(formatted)
-    }
-  }
+  return pretty
 
   function pretty (inputData) {
     let log
@@ -249,3 +238,40 @@ module.exports = function prettyFactory (options) {
     }
   }
 }
+
+function asMetaWrapper (dest) {
+  const parsed = Symbol('parsedChindings')
+
+  if (!dest) {
+    dest = process.stdout
+  } else if (!dest.write) {
+    throw new Error('the destination must be writable')
+  }
+
+  const pretty = this
+
+  return {
+    [Symbol.for('needsMetadata')]: true,
+    lastLevel: 0,
+    lastMsg: null,
+    lastObj: null,
+    lastLogger: null,
+    write (chunk) {
+      var chindings = this.lastLogger[parsed]
+
+      if (!chindings) {
+        chindings = JSON.parse('{"v":1' + this.lastLogger.chindings + '}')
+        this.lastLogger[parsed] = chindings
+      }
+
+      const obj = Object.assign({
+        level: this.lastLevel,
+        msg: this.lastMsg,
+        time: this.lastTime
+      }, chindings, this.lastObj)
+
+      const formatted = pretty(obj)
+      dest.write(formatted)
+    }
+  }
+}

package.json

@@ -39,7 +39,7 @@
     "through2": "^2.0.3"
   },
   "devDependencies": {
-    "pino": "^4.15.3",
+    "pino": "^4.16.0",
     "pre-commit": "^1.2.2",
     "snazzy": "^7.1.1",
     "standard": "^11.0.1",

test/basic.test.js

@@ -354,7 +354,26 @@ test('basic prettifier tests', (t) => {
         cb()
       }
     })
-    const prettyStream = prettyFactory({useMetadata: true, outputStream: dest})
+    const prettyStream = prettyFactory().asMetaWrapper(dest)
+    const log = pino({}, prettyStream)
+    log.info('foo')
+  })
+
+  t.test('can swap date and level position through meta stream', (t) => {
+    t.plan(1)
+
+    const dest = new Writable({
+      objectMode: true,
+      write (formatted, enc, cb) {
+        t.is(
+          formatted,
+          `INFO [${epoch}] (${pid} on ${hostname}): foo\n`
+        )
+        cb()
+      }
+    })
+
+    const prettyStream = prettyFactory({ levelFirst: true }).asMetaWrapper(dest)
     const log = pino({}, prettyStream)
     log.info('foo')
   })